Flameproofed regenerated cellulose and method

ABSTRACT

Flameproofed cellulose, especially regenerated cellulose, includes as a flameproofing agent an 0,0,0-triester of phosphoric acid or of thiophosphoric acid.

This is a continuation of application Ser. No. 708,378 filed July 26, 1976 pending in group.

The present invention relates to flameproofed cellulose.

In particular, the present invention provides flameproofed cellulose, preferably regenerated cellulose, including as a flameproofing agent a compound selected from 0,0,0-triesters of phosphoric acid and of thiophosphoric acid.

In the above and following, the term "including" or the like means the flameproofing agent is either coated on the surface of the cellulose or is incorporated therein.

Preferred flameproofed cellulose includes as a flameproofing agent a compound selected from 0,0,0-triesters of phosphoric acid and of thiophosphoric acid, wherein the phosphorus atom or atoms present in the molecule form part of a 1,3,2-dioxaphosphorinane ring.

Also preferred is flameproofed cellulose including as a flameproofing agent a compound selected from 0,0,0-triesters of phosphoric acid and of thiophosphoric acid, wherein the molecule of such a compound contains at least 2 phosphorus atoms in the form of a 0,0,0-triester of phosphoric acid and/or of thiophosphoric acid, and at least one of the phosphorus atoms is bound to three substituents which are not bound to one another, and the phosphoryl or thiophosphoryl radicals present in the molecule are bound to one another by a hydrocarbon bridge containing at least 2 carbon atoms.

The preferred flameproofed cellulose according to the present invention includes as a flameproofing agent a compound of formula I, ##STR1## in which

Y is oxygen or sulphur,

Z is a radical --R₂ (a) or ##STR2##

when Z is a radical (a), the R₁ 's together form a radical (c), ##STR3##

when Z is a radical (b), one, both or neither pair(s) of terminal R₁ 's form(s) a radical (c), and in any pair not forming a radical (c), each R₁, independently, is methyl; ethyl or propenyl, each unsubstituted or substituted with up to 3 halogen atoms or with a (C₁₋₆)alkoxy radical; (C₃₋₁₂)alkyl or (C₄₋₁₂)alkenyl, each unsubstituted or substituted with up to 4 halogen atoms; (C₅₋₈)cycloalkyl or (C₅₋₈)cycloalkyl-(C₁₋₄) alkyl, containing 7-9 carbon atoms in toto, each unsubstituted or ring substituted with 1 or 2 halogen atoms; or phenyl or phenyl-(C₁₋₄)alkyl, each unsubstituted or ring substituted with up to 5 halogen atoms or with up to 3 (C₁₋₃)alkyl radicals or with up to 3 (C₁₋₃)alkoxy radicals, with the proviso that a maximum of two moieties R₁ can be methyl,

R₂ is (C₂₋₁₈)alkyl, unsubstituted or substituted with up to 3 halogen atoms or with a (C₁₋₆) alkoxy radical; (C₃₋₁₀)alkenyl, unsubstituted or substituted with up to 3 halogen atoms; cyclohexyl; benzyl; or phenyl, unsubstituted or substituted with up to 5 substituents selected from chlorine and bromine atoms and methyl and ethyl radicals, with the proviso that when R₂ is (C₂₋₁₈)alkyl substituted with (C₁₋₆)alkoxy, such alkoxy substituent is not on the α-position of the alkyl radical,

R₃ is ethylene; (C₃₋₁₀)alkylene or (C₄₋₁₀) alkenylene, each straight or branched chain and unsubstituted or substituted with 1 or 2 halogen atoms; (C₄₋₁₀)alkynylene; or a divalent radical selected from those of formulae ##STR4## with the proviso that when R₃ is (C₃₋₁₀) alkylene, this cannot be alkyl-substituted methylene,

either each R₄, independently, is hydrogen, (C₁₋₄)alkyl, --CH₂ Cl, --CH₂ Br or phenyl,

and each R₅, independently, is (C₁₋₄)alkyl, --CH₂ Cl or --CH₂ Br,

or any R₄ and R₅, independently from any other R₄ and R₅, together with the carbon atom to which they are bound, form a cyclohexylidene, cyclohexenylidene or 3,4-dibromocyclohexylidene ring,

each R₆ and R₈, independently, is hydrogen or (C₁₋₄) alkyl,

each R₇, independently, is hydrogen or methyl, with the proviso (i) that when either or both of R₄ and R₅ in any radical (c) is --CH₂ Cl or --CH₂ Br, or both R₄ and R₅, together with the carbon atom to which they are bound form one of the rings indicated above, each of R₆, R₇ and R₈ in the same radical (c) is hydrogen, and (ii) that when Y is oxygen, each of R₄ and R₅, independently, in any radical (c) is --CH₂ Cl or --CH₂ Br or both R₄ and R₅, together with the carbon atom to which they are bound, form one of the rings indicated above,

each of m, m₁ and m₂ is 0, 1, 2, 3 or 4, with the proviso that the sum of m₁ and m₂ cannot exceed 4,

each of n₁ and n₂, independently, is an integer 1 to 6, and

X is oxygen or sulphur.

In the above definition of formula I, it is to be understood that the term "halogen" means chlorine and bromine.

When any moiety R₁ is unsubstituted or substituted alkyl, the alkyl radical preferably contains 1 to 6, more preferably 3 to 6, even more preferably 3 or 4, and most preferably 3 carbon atoms. For a substituted ethyl radical the substituent is preferably a single chlorine or bromine atom, and a (C₃₋₁₂) alkyl radical, when substituted, preferably bears up to 3 chlorine or bromine atoms. In the case of R₁ being propyl or isopropyl, this, when substituted, more preferably bears 1 or 2 chlorine or bromine atoms. Preferably, however, any alkyl radical signified by R₁ is unsubstituted.

When any R₁ is unsubstituted or substituted cycloalkyl, this is preferably unsubstituted cyclohexyl.

When any R₁ is unsubstituted or substituted phenylalkyl, this is preferably optionally substituted benzyl, and more preferably unsubstituted benzyl.

When any R₁ is unsubstituted or substituted phenyl, this, when substituted, preferably bears up to 3 halogen atoms or up to 3 alkyl radicals. Any alkyl substituent is preferably methyl. More preferably, substituted phenyl bears up to 3 chlorine atoms or a bromine atom in the para-position. The optionally substituted phenyl radical signified by R₁ is preferably, however, unsubstituted.

When R₂ is unsubstituted or substituted alkyl, the alkyl radical preferably contains 2 to 6 carbon atoms, and more preferably 2-5 carbon atoms. The substituents are preferably 1 or 2 halogen atoms or an alkoxy radical. Any halogen or alkoxy substituent is preferably bromine or methoxy, respectively.

When R₂ is unsubstituted or substituted alkenyl, the alkenyl radical preferably contains 3 to 6 carbon atoms. The preferred halogen substituents are bromine, and preferably the optionally substituted alkenyl radical is 2,3-dibromoprop-2-en-1-yl.

When R₂ is unsubstituted or substituted phenyl, this, when substituted, preferably bears up to 3 chlorine or up to 3 bromine atoms, or up to 3 methyl radicals.

When R₃ is unsubstituted or substituted (C₃₋₁₀)alkylene, the alkylene radical preferably contains 3 to 6, and more preferably 3 to 5 carbon atoms, and, when substituted, preferably bears 1 or 2 chlorine or 1 or 2 bromine atoms.

When R₃ is unsubstituted or substituted (C₄₋₁₀)alkenylene, the alkenylene radical preferably contains 4 carbon atoms, and, when substituted, preferably bears 2 chlorine or 2 bromine atoms.

When R₃ is (C₄₋₁₀)alkynylene, this preferably contains 4 carbon atoms.

Of the optionally bromo substituted phenylene radicals as R₃, the 1,4 isomer is preferred.

When R₃ is a radical of formula ##STR5## X therein is preferably sulphur.

When R₃ is a radical of formula ##STR6## each of n₁ and n₂, independently, is preferably 1 or 2.

When R₄ or R₅ is (C₁₋₄)alkyl, this is preferably (C₁₋₃) alkyl, and more preferably methyl.

Where Y is oxygen and each of R₄ and R₅, independently, in any radical (c), is --CH₂ Cl or --CH₂ Br, R₄ and R₅ are preferably identical, more preferably both --CH₂ Br.

When R₆ or R₈ is (C₁₋₄)alkyl, this is preferably methyl.

Y is preferably sulphur.

Of the significances for R₁ given in the definition of formula I above, the preferred are unsubstituted or substituted alkyl, cycloalkyl, phenylalkyl and phenyl, and, together with the other R₁ bound via oxygen atoms to the same phosphorus atom, a radical (c) as defined above. More preferably R₁ is unsubstituted or substituted alkyl, cycloalkyl or phenyl, or, together with the other R₁, as indicated above, a radical (c), and most preferably the two moieties R₁ bound via oxygen atoms to the same phosphorus atom form a radical (c).

When 2 moieties R₁ form a radical (c) and Y is sulphur, R₄ and R₅ in the radical (c) preferably each signify alkyl, --CH₂ Cl or --CH₂ Br or together with the carbon atom to which they are bound form a cyclohexylidene, cyclohexenylidene or 3,4-dibromocyclohexylidene ring, and more preferably each of R₄ and R₅ signifies alkyl, --CH₂ Cl or --CH₂ Br. Also in any radical (c), each of R₆, R₇ and R₈, independently, is preferably hydrogen.

R₂ is preferably unsubstituted or substituted alkenyl or phenyl.

R₃ is preferably unsubstituted or substituted alkylene or alkenylene, alkynylene, or one of the divalent radicals ##STR7## and most preferably unsubstituted or substituted alkylene or alkenylene, alkynylene or the divalent radical ##STR8##

When Z is a radical (b), the compounds of formula I are preferably symmetrical, i.e. either the two pairs of terminal R₁ 's form identical radicals (c), or the 4 R₁ 's have identical, individual significances.

The flameproofed cellulose of the present invention more preferably includes as a flameproofing agent a compound of formula Ia, ##STR9## in which

Z' is a radical --R₂ ' (a') or ##STR10##

when Z' is a radical (a'), the R₁ ''s together form a radical (c') ##STR11##

when Z' is a radical (b'), one, both or neither pair(s) of terminal R₁ ''s form(s) a radical (c'), and in any pair not forming a radical (c'), each R₁ ', independently, is ethyl; chloroethyl; bromoethyl; (C₃₋₁₂)alkyl, unsubstituted or substituted with up to 3 chlorine or up to 3 bromine atoms; cyclohexyl; benzyl; or phenyl, unsubstituted or substituted with up to 3 halogen atoms or up to 3 methyl radicals,

R₂ ' is (C₂₋₆)alkyl, unsubstituted or substituted with up to 3 halogen atoms or a methoxy radical; 2,3-dibromoprop-2-en-1-yl; cyclohexyl; benzyl; or phenyl, unsubstituted or substituted with up to 5 substituents selected from chlorine and bromine atoms and methyl and ethyl radicals, with the proviso that when R₂ ' is (C₂₋₆)alkyl substituted with methoxy, such methoxy substituent is not on the α-position of the alkyl radical,

R₃ ' is ethylene; (C₃₋₆)alkylene, straight or branched chain and unsubstituted or substituted with 1 or 2 chlorine or 1 or 2 bromine atoms; or a divalent radical selected from those of formulae ##STR12## with the proviso that when R₃ ' is (C₃₋₆) alkylene, this cannot be alkyl-substituted methylene,

each R₄ ' and R₅ ', independently, is (C₁₋₄)alkyl, --CH₂ Cl or --CH₂ Br,

or any R₄ ' and R₅ ', independently, together with the carbon atom to which they are bound, form a cyclohexylidene, cyclohexenylidene or 3,4-dibromocyclohexylidene ring, and

m is 0, 1, 2, 3 or 4.

The flameproofed cellulose of the present invention most preferably includes as a flameproofing agent a compound of formula Iba, Ibb or Ibc, ##STR13## in which

each R₁ " is n- or iso-propyl, unsubstituted or substituted with 1 or 2 chlorine or 1 or 2 bromine atoms; or (C₄₋₆)alkyl, unsubstituted or substituted with up to 3 chlorine or up to 3 bromine atoms,

R₂ " is 2,3-dibromoprop-2-en-1-yl, or phenyl, unsubstituted or substituted with up to 3 chlorine or bromine atoms or up to 3 methyl radicals,

R₃ " is (C₃₋₅)alkylene, straight or branched chain and unsubstituted or substituted with 1 or 2 chlorine or 1 or 2 bromine atoms; or a divalent radical selected from those of formulae ##STR14## with the proviso that when R₃ " is (C₃₋₅)alkylene, this cannot be alkyl-substituted methylene,

each of R₄ " and R₅ ", independently, is methyl, ethyl, --CH₂ Cl or --CH₂ Br, with the proviso that when R₄ " is --CH₂ Br, R₅ " is other than --CH₂ Cl and when R₅ " is --CH₂ Br, R₄ " is other than --CH₂ Cl.

Of the compounds of formula Iba, Ibb and Ibc, those of formula Ibb and Ibc are preferred.

The flameproofed cellulose indicated hereinbefore is preferably flameproofed regenerated cellulose.

The compounds of formula I', ##STR15## in which

R is ethylene; (C₃₋₁₀)alkylene, straight or branched chain and unsubstituted or substituted with 1 or 2 halogen atoms; or a divalent radical selected from those of formulae ##STR16## with the proviso that when R is (C₃₋₁₀) alkylene, this cannot be alkyl-substituted methylene,

either each R₉, independently, is (C₁₋₄)alkyl or phenyl,

and each R₁₀, independently, is hydrogen or (C₁₋₄)alkyl,

or any R₉ and R₁₀, independently of any other R₉ and R₁₀, together with the carbon atom to which they are bound, form a cyclohexylidene, cyclohexenylidene or 3,4-dibromocyclohexylidene ring,

and each of R₆, R₇ and R₈, independently, is as defined above, with the proviso that when each of the R₉ 's and R₁₀ 's is methyl, R is other than the divalent radical ##STR17## are new, and are also provided by the present invention.

The flame proofing agents used in the present invention which are not within the scope of formula I' are either known compounds and/or are producible in conventional manner from known starting materials by analogous processes to those for producing the known compounds.

In the above compounds of formula I', each R₉ and R₁₀, independently, is preferably alkyl, are preferably (C₁₋₃) alkyl, and most preferably methyl. R is preferably straight or branched chain (C₃₋₅)alkylene, unsubstituted or substituted with 1 or 2 chlorine or bromine atoms, or a divalent radical selected from those of formulae ##STR18##

The present invention further provides a process for the production of a compound of formula I', as defined above, which comprises reacting a compound of formula II, ##STR19## in which R, R₆, R₇, R₈, R₉ and R₁₀ are as defined above, with sulphur.

As will be appreciated, each reacting molecule of the compound of formula II reacts with 2 atoms of sulphur to produce the desired product of formula I'.

This reaction may be effected under conventional reaction conditions known from analogous processes involving the same reaction principle. In general, it is suitably conducted in the presence of an inert solvent, preferably toluene, in a temperature range of 20° to 140° C., preferably 20° to 80° C.

The intermediates of formula II, as defined above, are new, and are also provided by the present invention. They may be produced by a process which comprises reacting a compound or a mixture of two compounds of formula III, ##STR20## in which R₆, R₇, R₈, R₉ and R₁₀ are as defined above, with a compound of formula IV,

    HO--R--OH                                                  IV

in which R is as defined above.

As will be appreciated, every 2 reacting molecules of the compound of formula III react with 1 molecule of the compound of formula IV to produce the desired product of formula II.

This reaction may be effected under conventional reaction conditions known from analogous processes involving the same reaction principle. In general, it is suitably conducted in the presence of an acid binding agent, preferably a tertiary amine, e.g. triethylamine or pyridine.

The intermediates of formulae III and IV, as defined above, are either known, readily available compounds or may be produced in conventional manner from known starting materials by analogous processes to those for producing the known compounds.

The present invention further provides a method of producing flameproofed cellulose comprising treating the cellulose with a flameproofing-effective amount of a compound selected from 0,0,0-triesters of phosphoric acid and of thiophosphoric acid or of any above-indicated preferred member of these classes of esters.

The flameproofing agents indicated above are useful for the flameproofing of regenerated cellulose. For this purpose cellulose is brought into solution in known manner, e.g. converted into a soluble derivative, e.g. with tetramine copper (II) hydroxide or according to the xanthate method.

To the cellulose solution produced in this way is added the flameproofing agent. The addition can be effected directly, continuously or discontinuously, with vigorous stirring of the cellulose solution. Alternatively the flameproofing agent may be first dispersed in water and added to the cellulose solution as a fine dispersion. In all cases it is advantageous to add conventional dispersion stabilisers and dispersing agents. The technically important properties of the precipitated cellulose, except the flame retardancy, are only insignificantly affected by the addition of the flameproofing agent. 5 to 35 weight percent of the flameproofing agent based on the weight of α-cellulose, can, for example, be distributed in the cellulose solution. Preferably amounts of 8-25% by weight are used. The regenerated cellulose is precipitated from the cellulose solution, which contains the flameproofing agent in known manner and in shaped form. As shaping comes above all the formation of filaments or sheets through passage of the cellulose solution into a precipitation bath with use of fine nozzles or slots. Normal precipitation baths can be used in the production of regenerated cellulose fibres or sheets. Practically the quantitative amount of the flameproofing agent contained in the cellulose solution is included in the precipitated regenerated cellulose. It is also possible to use other flameproofing substances as well as the flameproofing agents indicated above. Such compounds are, e.g. reaction products of a phosphorus nitrile chloride with glycols, e.g. neopentyl glycol or analogous compounds, or cyclodiphosphazanes or thionocyclodiphosphazanes, e.g. 2,4-dianilino-2,4-dioxo-1,3-diphenylcyclodiphosphazane.

The proportion of these further components can be varied within wide limits and can constitute up to 90% of the total amount of flameproofing composition present. Preferably 10-70%, especially 15-60% of the reaction product of phosphornitrile chloride and glycol or of a cyclodiphosphazane or thionocyclodiphosphazane, based upon the total weight of flameproofing composition, is used, whereby the latter is used in the amount indicated above.

For natural fibres the flameproofing agents used according to the invention are applied externally from a solvent or in the form of an aqueous dispersion in conventional manner. With mixtures of natural and synthetic fibres each fibrous material can be treated independently and then mixed, or the mixture itself, e.g. polyester-cotton blend, can be treated.

The present invention is illustrated by the following Examples, in which parts and percentages are by weight.

EXAMPLE 1

(a) 2-Chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane is produced according to the method of H. J. Lucas et al., J.A.C.S. 72, page 5491, and is a colourless liquid of boiling point 43°-46° C./2 atmospheres.

(b) To a stirred mixture of 147.6 parts of trans-2,3-dibromo-2-butene-1,4-diol and 1040 parts of toluene under an atmosphere of nitrogen are added dropwise 202.8 parts of 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane at room temperature over a period of 15 minutes. The reaction mixture is cooled with ice-water and 121.2 parts of triethylamine are added dropwise at such a rate that the temperature does not exceed 30° C. During the addition, a white suspension is formed.

The reaction mixture is then stirred for 1 hour, heated to 45° C. and stirred for a further 21/2 hours at this temperature.

The mixture is filtered to remove the triethylamine hydrochloride from the reaction mixture, and this is washed with toluene, followed by petroleum ether. After concentrating the filtrate to dryness, 241.7 parts of a crude product of the formula 1b ##STR21## are produced, and this is purified by recrystallisation from ligroin (b.p. 80°-95° C.), affording a product of m.p. 92°-96° C.

(c) To a stirred solution of 200 parts of the purified product of formula 1b in 865 parts of toluene under an atmosphere of nitrogen are added 25.1 parts of sulphur powder in one amount at room temperature. The reaction mixture is then heated to boiling point and refluxed at this temperature for 4 hours. The clear, yellow reaction solution is then cooled to about 50° C. and the resulting white crystalline product removed by filtration. The crude product is washed with toluene and afterwards petroleum ether.

Obtained are 145 parts of the crude compound, No. 32 of table 1 following, which is purified by recrystallisation from toluene. The purified product has a melting point of 174°-177° C.

EXAMPLE 2

To 200 parts of a cellulose solution based on xanthate, which solution contains 18 parts of α-cellulose, are added with stirring 15.7 parts of a 23% aqueous dispersion of the compound No. 32 of Table 1. The dispersion is produced in the following way:

40 parts of the compound No. 32, 10 parts of a dispersing agent based on sodium naphthalene sulphonate and 110 parts of water are ground with sand in the presence of 160 parts of quartzite beads for 4 hours. The grinding is effected with ice-cooling at 1500 revolutions per minute of the grinder. After removal of the quartzite beads by filtration 140 parts of a dispersion containing 23% of the active ingredient are obtained.

The cellulose solution containing the active ingredient is extruded through spinerettes according to a conventional procedure into a precipitation bath containing, per liter, 125 g of sulphuric acid, 240 g of anhydrous sodium sulphate and 12 g anhydrous zinc sulphate. The fibres produced are thoroughly washed and formed into knitted products.

EXAMPLE 3

To 200 parts of a cellulose solution based on xanthate, which solution contains 18 parts of α-cellulose, are added consecutively 7.85 parts of an aqueous dispersion of the compound, No. 32 of Table 1 and 9 parts of a 20% aqueous dispersion of 2,4-dianilino-2,4-dioxo-1,3-diphenyl-cyclodiphosphazane with stirring. The production of the resulting flameproofed cellulose is effected in analogous manner to that described in the previous Example.

The compounds in Table 1 following are produced in an analogous manner to that described in Example 1 and are used as described in Examples 2 and 3.

                                      TABLE 1                                      __________________________________________________________________________     No.                                                                               formula                       m.p. °C.                               __________________________________________________________________________         ##STR22##                    64-5                                          2                                                                                  ##STR23##                    b.p. 124/2 atm.                               3                                                                                  ##STR24##                    88-90                                         4                                                                                  ##STR25##                    b.p. 125-7/ 2 atm.                            5                                                                                  ##STR26##                    b.p. 140-2/ 2 atm.                            6                                                                                  ##STR27##                    b.p. 142-4/2 atm.                             7                                                                                  ##STR28##                    83-5                                          8                                                                                  ##STR29##                    121-3                                         9                                                                                  ##STR30##                    49-50                                         10                                                                                 ##STR31##                    51-3                                          11                                                                                 ##STR32##                    100-1                                         12                                                                                 ##STR33##                    162-5                                         13                                                                                 ##STR34##                    250-1                                         14                                                                                 ##STR35##                    72-3                                          15                                                                                 ##STR36##                    oil                                           16                                                                                 ##STR37##                    oil                                           17                                                                                 ##STR38##                    oil                                           18                                                                                 ##STR39##                    oil                                           19                                                                                 ##STR40##                    53-5                                          20                                                                                 ##STR41##                    124-5                                         21                                                                                 ##STR42##                    oil                                           22                                                                                 ##STR43##                    62-5                                          23                                                                                 ##STR44##                    225                                           24                                                                                 ##STR45##                    176-9                                         25                                                                                 ##STR46##                    125-7                                         26                                                                                 ##STR47##                    166-9                                         27                                                                                 ##STR48##                    164-5                                         28                                                                                 ##STR49##                    171-3                                         29                                                                                 ##STR50##                    106-7                                         30                                                                                 ##STR51##                    228-31                                        31                                                                                 ##STR52##                    138-41                                        32                                                                                 ##STR53##                    174-7                                         33                                                                                 ##STR54##                    b.p. 125/0.12 atm.                            34                                                                                 ##STR55##                    oil                                           35                                                                                 ##STR56##                    oil                                           __________________________________________________________________________ 

What is claimed is:
 1. Flameproofed regenerated cellulose containing, as a flameproofing agent, an effective amount of a compound of formula, ##STR57## wherein R₃ " is straight or branched chain C₃ -C₅ alkylene; or a divalent radical selected from ##STR58## with the proviso that when R₃ " is straight or branched chain C₃ -C₅ alkylene, it is other than alkyl-substituted methylene; andeach of R₄ " and R₅ " is, independently, methyl; ethyl; --CH₂ Cl; or --CH₂ Br; with the provisos that: (a) when R₄ " is --CH₂ Br, R₅ " is other than --CH₂ Cl; and (b) when R₅ " is CH₂ Br, R₄ " is other than --CH₂ Cl.
 2. Flameproofed regenerated cellulose according to claim 1 containing, as a flameproofing agent, the compound of the formula ##STR59##
 3. Flameproofed regenerated cellulose according to claim 1 containing, as a flameproofing agent, the compound of the formula ##STR60##
 4. Flameproofed regenerated cellulose according to claim 1 containing, as a flameproofing agent, the compound of the formula ##STR61##
 5. A method for producing flameproofed regenerated cellulose comprising regenerating cellulose from a cellulose-containing medium containing a flameproofing effective amount of a flameproofing agent of the formula ##STR62## wherein R₃ " is straight or branched chain C₃ -C₅ alkylene; or a divalent radical selected from ##STR63## with the proviso that when R₃ " is straight or branched chain C₃ -C₅ alkylene, it is other than alkyl-substituted methylene; andeach of R₄ " and R₅ " is, independently, methyl; ethyl; --CH₂ Cl; or --CH₂ Br; with the provisos that: (a) when R₄ " is --CH₂ Br, R₅ " is other than --CH₂ Cl; and (b) when R₅ " is CH₂ Br, R₄ " is other than --CH₂ Cl.
 6. A method according to claim 5, wherein the amount of said flameproofing agent is from 8% to 25% of the weight of the cellulose in the cellulose-containing medium.
 7. A method according to claim 5 wherein the cellulose-containing medium contains, in addition to the flameproofing agent, a reaction product of a phosphorus nitrile chloride with a glycol, a cyclodiphosphazane or a thionocyclodiphosphazane.
 8. A method for producing flameproofed regenerated cellulose comprising applying to regenerated cellulose a solution or an aqueous dispersion containing a flameproofing effective amount of a flameproofing agent of the formula ##STR64## wherein R₃ " is straight or branched chain C₃ -C₅ alkylene; or a divalent radical selected from ##STR65## with the proviso that when R₃ " is straight or branched chain C₃ -C₅ alkylene, it is other than alkyl-substituted methylene; andeach of R₄ " and R₅ " is, independently, methyl; ethyl; --CH₂ Cl; or --CH₂ Br; with the provisos that: (a) when R₄ " is --CH₂ Br, R₅ " is other than --CH₂ Cl; and (b) when R₅ " is CH₂ Br, R₄ " is other than --CH₂ Cl. 